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[MSan] Ensure argument shadow initialized on memcpy 

We need to explicitly query the shadow here, because it is lazily
initialized for byval arguments. Without opaque pointers this used to
mostly work out, because there would be a bitcast to `i8*` present, and
that would query, and copy in case of byval, the argument shadow.

Reviewed By: vitalybuka, eugenis

Differential Revision: https://reviews.llvm.org/D123602
This commit is contained in:
Nikita Popov 2022-04-12 13:45:53 -07:00 committed by Vitaly Buka
parent efdc90baaa
commit 0adadfa68f
2 changed files with 37 additions and 0 deletions
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2
llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
View File

@ -2570,6 +2570,7 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
///
/// Similar situation exists for memcpy and memset.
void visitMemMoveInst(MemMoveInst &I) {
getShadow(I.getArgOperand(1)); // Ensure shadow initialized
IRBuilder<> IRB(&I);
IRB.CreateCall(
MS.MemmoveFn,
@ -2584,6 +2585,7 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
// FIXME: consider doing manual inline for small constant sizes and proper
// alignment.
void visitMemCpyInst(MemCpyInst &I) {
getShadow(I.getArgOperand(1)); // Ensure shadow initialized
IRBuilder<> IRB(&I);
IRB.CreateCall(
MS.MemcpyFn,

35
llvm/test/Instrumentation/MemorySanitizer/opaque-ptr.ll Normal file
View File

@ -0,0 +1,35 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -S -passes=msan < %s | FileCheck %s
target triple = "x86_64-unknown-linux-gnu"
define void @test_memcpy(ptr %p, ptr byval(i32) %p2) sanitize_memory {
; CHECK-LABEL: @test_memcpy(
; CHECK-NEXT: [[TMP1:%.*]] = ptrtoint ptr [[P2:%.*]] to i64
; CHECK-NEXT: [[TMP2:%.*]] = xor i64 [[TMP1]], 87960930222080
; CHECK-NEXT: [[TMP3:%.*]] = inttoptr i64 [[TMP2]] to ptr
; CHECK-NEXT: call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[TMP3]], ptr align 4 inttoptr (i64 add (i64 ptrtoint (ptr @__msan_param_tls to i64), i64 8) to ptr), i64 4, i1 false)
; CHECK-NEXT: call void @llvm.donothing()
; CHECK-NEXT: [[TMP4:%.*]] = call ptr @__msan_memcpy(ptr [[P:%.*]], ptr [[P2]], i64 4)
; CHECK-NEXT: ret void
;
call void @llvm.memcpy.p0.p0.i64(i8* %p, i8* %p2, i64 4, i1 false)
ret void
}
define void @test_memmove(ptr %p, ptr byval(i32) %p2) sanitize_memory {
; CHECK-LABEL: @test_memmove(
; CHECK-NEXT: [[TMP1:%.*]] = ptrtoint ptr [[P2:%.*]] to i64
; CHECK-NEXT: [[TMP2:%.*]] = xor i64 [[TMP1]], 87960930222080
; CHECK-NEXT: [[TMP3:%.*]] = inttoptr i64 [[TMP2]] to ptr
; CHECK-NEXT: call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[TMP3]], ptr align 4 inttoptr (i64 add (i64 ptrtoint (ptr @__msan_param_tls to i64), i64 8) to ptr), i64 4, i1 false)
; CHECK-NEXT: call void @llvm.donothing()
; CHECK-NEXT: [[TMP4:%.*]] = call ptr @__msan_memmove(ptr [[P:%.*]], ptr [[P2]], i64 4)
; CHECK-NEXT: ret void
;
call void @llvm.memmove.p0.p0.i64(i8* %p, i8* %p2, i64 4, i1 false)
ret void
}
declare void @llvm.memcpy.p0.p0.i64(i8*, i8*, i64, i1)
declare void @llvm.memmove.p0.p0.i64(i8*, i8*, i64, i1)